man I hunt in GA and I have had the same thing happen after opening day thay shutup the singles u are seeing are probally nesting and have already bred. Dont over hunt the area let it rest otherwise the gobblers will get call shy and will actually run in the opposite direction when they hear u call. Try roosting them or going in mid afternoon when the gobblers part ways with the hens he flew down with that morning. They wont gobble as much in the afternoon so dont over call. ( a few clucks and yelps every 10-15 mins should do fine)